Answer to Question #291266 in Cell Biology for kivedo

Question

The organelle labelled mitochondria is involved in an important cell process.

Identify the process that takes place in this organelle’s inner matrix.

Answer 1

Mitochondria is involved in an important cell process called Citric acid cycle or tricarboxylic acid cycle (TCA) or the Kreb's cycle. It is a series of chemical reactions to release stored energy through the oxidation of acetyl CoA which is derived from carbohydrates, proteins and fats. This cycle is termed the citric acid cycle as the first metabolic intermediate formed in the cycle is citric acid. The Kreb's cycle is used by organisms with aerobic or anaerobic respiration, to generate energy.

    The cycle consumes acetate (in the form of acetyl CoA) and water, reduces NAD⁺ to NADH, releasing carbon dioxide (CO₂) . The NADH generated by the citric acid cycle is fed into the oxidative phosphorylation (electron transport chain) pathway. The net result of these two closely linked pathways is the oxidation of nutrients to produce chemical energy in the form of ATP.

• Steps of Kreb's Cycle:

There are some basic steps in the citric acid cycle, as outlined below. The cycle is continuously supplied with new carbon in the form of acetyl CoA.

The enzymes that help the cycle to preceed are:

1. Aconitase
2. Icocitrate dehydrogenase
3. α
4. α-Ketoglutarate dehydrogenase complex
5. Succinyl CoA synthetase
6. Succinate dehydrogenase
7. Fumarase
8. Malate dehydrogenase
9. Citrate Synthase

*(Citrate synthase is the first enzyme in this cycle. The numbering should be started from Citrate Synthase in the picture)

• Kreb's Cycle inputs and outputs per glucose molecule: